Washington: Like humans, female Asian elephants recognise their friends even after living apart for a long time, says a new research. They may change their day to day associations but maintain a larger, stable pool of friends from which they pick their companions, University of Pennsylvania research says.

The researchers followed friendships in 100 female adult Asian elephants in the Uda Walawe National Park in Sri Lanka for five seasons, the journal BMC Ecology reports.

They analyzed how these relationships changed over a period of time.

These elephants tended to congregate in groups of three adult females and there could be as many as 17 in a single group, says a Pennsylvania statement.

Social strategies were also variable, with some females always being seen in each other's company while others were social butterflies who frequently changed companions.

Shermin de Silva, who led the study, explained, 'Elephants are able to track one another over large distances by calling to each other and using their sense of smell.'

Some 16 percent completely changed their 'top five' friends over the course of the study. Elephants who had few companions were very faithful to them whereas those who had many tended to be less loyal.(Agencies)